Experimental Characterization and Acoustic Correction of a Multipurpose Performance Hall: The Italian Theatre “Cavallino Bianco”

Abstract

This study presents the retrofit acoustic dq1esign of the Italian theatre “Cavallino Bianco”. In its historical configuration, the hall had a curved roof with a pressed-plant fiber ceiling, which was demolished and replaced with a wooden roof without a false ceiling, leading to an increase in volume and a worsening of the reverberation time. This study proposed the realization of a wave ceiling and the application of sound-absorbing and reflecting panels on the walls, which have already been implemented. These modifications have affected the acoustic characterization of the theatre, as shown both through on-site measurements during the main construction phases and through numerical simulations. The reverberation time, clarity index, and speech transmission index (STI) are evaluated considering all the variations in the hall over different construction times, and the optimal solution is identified with regard to different specific uses. The final configuration with the new roof, by reducing the volume of the hall and using sound-absorbing materials, significantly reduces the reverberation time (e.g., at 2000 Hz, this reduction is from 2.33 to 1.47). In addition, the hall at full capacity with chairs and people shows evident improvement in terms of the clarity index, allowing the theatre to be used for a wide range of musical genres such as instrumental, symphonic, and opera performances. As regards the Combos 00 (concrete roof without vertical sound acoustic panels) and 01-a/b/c (wooden roof with draped curtains), the STI values are never lower than 0.42 and never higher than 0.70; therefore, the room never experiences poor or excellent conditions at any point. The Combos 01-a and 01-b, which have a non-performing C80, have a good STI index, confirming the difficulty of achieving a configuration that can be optimal a variety of uses. Combo 01 (wooden roof without vertical sound acoustic panels and no draped curtains), which has a good C80 value, presents a lower STI value, with an average performance. The STI values of Combo 02-a (characterized by wave false ceiling and vertical sound acoustic panels) are never lower than 0.52 and never higher than 0.60; therefore, neither poor nor excellent conditions are experienced in the room, but there is still a slight improvement over the combos 00 and 01.